Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for restricting a frequency in a wireless communication system.
Related Art
Universal mobile telecommunications system (UMTS) is a 3rd generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). A long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.
In order to allow users to access various networks and services ubiquitously, an increasing number of user equipments (UEs) are equipped with multiple radio transceivers. For example, a UE may be equipped with LTE, Wi-Fi, Bluetooth (BT) transceivers, etc., for wireless communication systems, and global navigation satellite system (GNSS) receivers. For example, a UE may be equipped with a LTE module and a Bluetooth module in order to receive a voice over Internet (VoIP) services and multimedia services using a Bluetooth earphone. A UE may be equipped with a LTE module and a Wi-Fi module in order to distribute traffics. A UE may be equipped with a LTE module and a GNSS module in order to acquire location information additionally.
Due to proximity of multiple radio transceivers within the same UE, the transmit power of one transmitter may be much higher than the received power level of another receiver. By means of filter technologies and sufficient frequency separation, interference between two transceivers may be avoided. But, due to extreme proximity of multiple radio transceivers within the same UE operating on adjacent frequencies or sub-harmonic frequencies, the interference power coming from a transmitter of the collocated radio may be much higher than the actual received power level of the desired signal for a receiver. This situation causes in-device coexistence (IDC) interference. The challenge lies in avoiding or minimizing IDC interference between those collocated radio transceivers, as current state-of-the-art filter technology might not provide sufficient rejection for certain scenarios. Therefore, solving the interference problem by single generic radio frequency (RF) design may not always be possible and alternative methods needs to be considered.
Interworking of 3GPP/wireless local area network (WLAN) may be introduced have been discussed. The IDC interference in interworking of 3GPP/WLAN may be considered, and accordingly, a method for avoiding the IDC interference in interworking of 3GPP/WLAN may be required.